Electrode for a lithium cell

ABSTRACT

This invention relates to a positive electrode for an electrochemical cell or battery, and to an electrochemical cell or battery; the invention relates more specifically to a positive electrode for a non-aqueous lithium cell or battery when the electrode is used therein. The positive electrode includes a composite metal oxide containing AgV 3 O 8  as one component and one or more other components consisting of LiV 3 O 8 , Ag 2 V 4 O 11 , MnO 2 , CF x , AgF or Ag 2 O to increase the energy density of the cell, optionally in the presence of silver powder and/or silver foil to assist in current collection at the electrode and to improve the power capability of the cell or battery.

RELATED APPLICATIONS

This application, pursuant to 37 C.F.R. 1.78(c), claims priority basedon provisional application Ser. No. 60/409,440 filed on Sep. 10, 2002.

The United States Government has rights in this invention pursuant toContract No. W-31-109-ENG-38 between the U.S. Department of Energy (DOE)and The University of Chicago representing Argonne National Laboratory.

FIELD OF INVENTION

This invention relates to electrochemical cells and batteries and moreparticularly to improved positive electrode materials for non-aqueouslithium cells. The electrodes consist of a composite system having asone component a silver-vanadium-oxide of nominal composition AgV₃O₈. Thepredominant, but not exclusive, field of use is for primary(non-rechargeable) lithium batteries with particular emphasis onpowering medical devices such as cardiac pacemakers, defibrillators andmedical pumps.

BACKGROUND OF THE INVENTION

Lithium electrochemical cells and batteries are being widely exploitedas power sources for numerous applications because of their high energyand power density, for example, in consumer electronics such as laptopcomputers and cellular phones, in medical devices such as cardiacpacemakers and defibrillators and in electric and hybrid electricvehicles.

Silver vanadium oxides, particularly Ag₂V₄O₁₁, are well known aspositive electrode materials for primary lithium cells for poweringcardiac defibrillators in the medical industry. For example, U.S. Pat.Nos. 4,310,609 and 4,391,729 discloses the use of an electrochemicalcell having as its positive electrode a composite oxide matrixconsisting of a vanadium oxide chemically reacted with a group IB, IIB,IIIB, IVB, VB, VIB, VIIB and VIII metal, and most specifically with asilver containing compound. U.S. Pat. No. 4,391,729 also discloses amethod of making such a cathode. In addition, several scientific papersdescribing the structural and electrochemical properties of Ag₂V₄O₁₁ andAg₂V₄O_(11−x) and AgV₃O₈ have appeared in the literature, such as thatof Takeuchi et al (Journal of Power Sources, Volume 21, page 133 (1987);Leising et al (Chemistry of Materials, Volume 5, page 738 (1993));Leising et al (Chemistry of Materials, Volume 6, page 489 (1994));Garcia-Alvarado et al (Solid State Ionics, Volume 73, page 247 (1994));Kawakita et al (Solid State Ionics, Volume 99, page 71 (1997)); Rozieret al, (Journal of Solid State Chemistry, Volume 134, page 294 (1997)).Moreover, lithium vanadium oxide electrodes, such as Li_(1.2)V₃O₈, arealso well known for their good electrochemical properties inrechargeable or secondary lithium cells. For example, U.S. Pat. No.5,039,582 discloses the use of an amorphous form of LiV₃O₈ as a positiveelectrode in a lithium cell, and U.S. Pat. No. 5,336,572 discloses theuse of M_(x)V₃O₈ positive electrodes for lithium cells, where M is amonovalent or multivalent metal cation. In addition, numerous researchpapers on the structural and electrochemical properties of Li_(x)V₃O₈materials have been written, such as that of Wadsley et al (ActaCrystallographica, Volume 10, page 261 (1957)); de Picciotto et al(Solid State Ionics, Volume 62, page 297 (1993); Panera et al (Journalof the Electrochemical Society, Volume 130, page 1225 (1983)); West etal (Journal of the Electrochemical Society, Volume 143, page 820(1996)). Spahr et al has disclosed the use of NaV₃O₈ as a cathode in alithium cell (Journal of the Electrochemical Society, Volume 145, page421 (1998)).

A problem that is encountered with state-of-the-art Ag₂V₄O₁₁ cathodes inlithium cells is the deterioration of electrochemical performance,particularly the ability of the cells to deliver acceptable pulse powerbefore the cell has reached the end of its expected calendar andoperating life. It can therefore be readily understood that suchlimitations of Li/Ag₂V₄O₁₁ cells are of great concern when used to powercardiac defibrillators in the human body. Such limitations negativelyaffect product reliability and necessitate a continual monitoring of thecells while implanted in patients to ensure a timely replacement of thecells before they prematurely reach the end of discharge. There istherefore a great need to improve the electrochemical properties andoperating life of silver-vanadium-oxide electrodes for lithium cells andbatteries, particularly for use in life-supporting medical devices, suchas cardiac defibrillators.

SUMMARY OF THE INVENTION

This invention relates to a positive electrode for an electrochemicalcell or battery, and to an electrochemical cell or battery; theinvention relates more specifically to an improved positive electrodefor a non-aqueous lithium cell or battery when the electrode is usedtherein, the positive electrode comprising a composite metal oxidecontaining AgV₃O₈ as one component and one or more components selectedfrom LiV₃O₈, Ag₂V₄O₁₁, MnO₂, CF_(x), AgF or Ag₂O to increase the energydensity of the cell optionally in the presence of silver powder and/orsilver foil to assist in current collection at the electrode and toimprove the power capability of the cell or battery. When the compositeelectrode consists of AgV₃O₈ and LiV₃O₈ components, the electrode hasthe general formula xAgV₃O₈.(1−x)LiV₃O₈ (or alternativelyAg_(x)Li_(1−x)V₃O₈). The invention extends to include substitutedAg_(x)Li_(1−x)V_(3−y)M_(y)O₈ electrode compounds in which the limits ofx and y are 0<x<1, 0<y<1.5, respectively, and where M is a monovalent ormultivalent ion of one or more transition metals and most preferably oneor more of Ti, Y, Zr, Nb and Mo ions.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention consists of certain novel features and a combination ofparts hereinafter fully described, illustrated in the accompanyingdrawings, and particularly pointed out in the appended claims, it beingunderstood that various changes in the details may be made withoutdeparting from the spirit, or sacrificing any of the advantages of thepresent invention.

FIG. 1 depicts a schematic illustration of a LiV₃O₈ or AgV₃O₈ structure;

FIG. 2 depicts the powder X-ray diffraction pattern of AgV₃O₈;

FIG. 3 depicts the powder X-ray diffraction pattern of LiV₃O₈;

FIG. 4 depicts the powder X-ray diffraction pattern of axAgV₃O₈.(1−x)LiV₃O₈ composite;

FIG. 5 depicts the powder X-ray diffraction pattern of Ag₂V₄O₁₁;

FIG. 6 depicts the powder X-ray diffraction pattern of a AgV₃O₈/Ag₂V₄O₁₁composite

FIG. 7 depicts the electrochemical (pulsed current) profile for thedischarge of a Li/AgV₃O₈ cell;

FIG. 8 depicts the electrochemical (pulsed current) profile for thedischarge of a Li/LiV₃O₈ cell;

FIG. 9 depicts the electrochemical (pulsed current) profile for thedischarge of a Li/xAgV₃O₈.(1−x)LiV₃O₈ cell;

FIG. 10 depicts the electrochemical (pulsed current) profile for thedischarge of a Li/AgV₃O₈, MnO₂ cell;

FIG. 11 depicts the electrochemical (pulsed current) profile for thedischarge of a Li/AgV₃O₈, Ag₂O cell;

FIG. 12 depicts the electrochemical (pulsed current) profile for thedischarge of a Li/AgV₃O₈, Ag cell;

FIG. 13 depicts a schematic illustration of an electrochemical cell; and

FIG. 14 depicts a schematic illustration of an example of a batteryemploying the cells of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

State-of-the-art cardiac defibrillators are powered by lithium batteriesin conjunction with electrolytic capacitors. The batteries contain ametallic lithium negative electrode, a silver-vanadium oxide positiveelectrode of composition Ag₂V₄O₁₁, and a non-aqueous liquid electrolyteconsisting of a lithium salt such as LiAsF₆ dissolved in an organicsolvent, such as a 50:50 mixture of propylene carbonate anddimethoxyethane. Li/Ag₂V₄O₁₁ cells discharge by an electrochemicalprocess that involves lithium insertion into the crystal lattice ofAg₂V₄O₁₁ with a simultaneous reduction of the silver ions and theirconcomitant extrusion from the crystal lattice. Thereafter, lithiuminsertion is accompanied by the reduction of the vanadium ions withinthe structure, ideally from V⁵⁺ to V⁴⁺. Thus, the reaction can bebroadly defined in the ideal case as taking place in two main steps:Li+Ag₂V₄O₁₁→Li₂V₄O₁₁+2Ag  (Step 1: Silver displacement)xLi+Li₂V₄O₁₁→Li_(2+x)V₄O₁₁ (x _(max)≈5)  (Step 2: Lithium insertion)

One of the major limitations of Li/Ag₂V₄O₁₁ cells is that they losetheir capability of providing the necessary power particularly after thereaction described in Step 1 has occurred, and when cells are allowed tostand for prolonged periods of time. It is believed that this loss inpower may be attributed, at least in part, to the Ag₂V₄O₁₁ positiveelectrode, and in particular, that it may be attributed to the fact thatat the end of Step 1, a metastable phase of composition Li₂V₄O₁₁ isformed. This metastability is reflected by the fact that it has not beenpossible to synthesize a Li₂V₄O₁₁ phase that is isostructural withAg₂V₄O₁₁ by independent chemical methods in the laboratory. Attempts tosynthesize a Li₂V₄O₁₁ phase in the laboratory, for example, by reactingAg₂V₄O₁₁ with n-butyllithium, have failed; these attempts have alwaysyielded other stable lithium-vanadium-oxide phases such as LiVO₃ andLiV₃O₈. This finding indicates that the power fade may at least bepartly attributed to a decay of the “Li₂V₄O₁₁” phase that is generatedelectrochemically during Step 1 into other more stablelithium-vanadium-oxide compounds.

This invention addresses this problem and advocates the use ofalternative electrode materials for Ag₂V₄O₁₁ electrodes, andparticularly composite electrodes in which AgV₃O₈ is one component ofthe electrode. In one embodiment of the invention, the electrode is acomposite electrode of AgV₃O₈ and LiV₃O₈ having the general formulaxAgV₃O₈.(1−x)LiV₃O₈ (or alternatively, Ag_(x)Li_(1−x)V₃O₈) for 0<x<1.Because the of AgV₃O₈ and LiV₃O₈ are similar, it is envisaged that asolid solution or mixture of phases may exist between AgV₃O₈ and LiV₃O₈,the latter phase being known to be an extremely stable material and easyto synthesize by chemical methods in the laboratory, unlike hypothetical“Li₂V₄O₁₁”. The advantage of such a system is that after displacement orextrusion of the Ag from the Ag_(x)Li_(1−x)V₃O₈ structure or compositestructure (analogous to Step 1 given for Ag₂V₄O₁₁ above) the compound,LiV₃O₈, is generated that is stable in the cell environment;furthermore, it is known that the LiV₃O₈ thus formed, can accommodateadditional lithium without disruption of the V₃O₈ framework to acomposition Li_(1+y)V₃O₈, where y_(max)=4. Thus for an undopedelectrode, the two main discharge reactions for an Ag_(x)Li_(1−x)V₃O₈electrode would ideally be (by analogy to Steps 1 and 2 above):xLi+Ag_(x)Li_(1−x)V₃O₈→LiV₃O₈ +xAg  (Step 1: Silver displacement)yLi+LiV₃O₈→Li_(1+y)V₃O₈ (y _(max)=4)  (Step 2: Lithium insertion)

It will be appreciated by those skilled in the art, that in practicewhen AgV₃O₈ and LiV₃O₈ compounds are synthesized, their stoichiometriesmay vary slightly from their numerically ideal formulae. For example, ithas been well established that the thermodynamically stablestoichiometry of the lithium-vanadium-oxide compound when synthesized atapproximately 600° C. is Li_(1.2)V₃O₈. The 3 vanadium ions of theformula unit reside in either octahedral or square-pyramidal sites(shown as connected polyhedra in FIG. 1). Of the 1.2 lithium ions, 1.0Li ions occupy octahedral sites (shown as black dots in FIG. 1) and theremaining 0.2 Li ions partially occupy tetrahedral sites (not shown inFIG. 1). It is therefore possible that small deviations in stoichiometrymay also occur for AgV₃O₈. This invention therefore allows for suchdeviations in stoichiometry and the simplified formulaxAgV₃O₈.(1−x)LiV₃O₈, alternatively Ag_(x)Li_(1−x)V₃O₈, is merely usedfor convenience.

In a second embodiment, this invention includes substitutedAg_(x)Li_(1−x)V_(3−y)M_(y)O₈ electrode compounds in which the limits ofx and y are 0<x<1, 0<y<1.5, respectively, and where M is a monovalent ormultivalent ion of one or more transition metals. Such metalsubstitutions in LiV_(3−y)M_(y)O₈ compounds, in which M can, forexample, be selected typically from one or more of Ti, Y, Zr, Nb and Moas already disclosed in U.S. Pat. No. 6,322,928, can be used to impartgreater stability to the LiV₃O₈ electrode structure. It is believed thatsuch substitutions could also be used to stabilize the V₃O₈ framework ofthe Ag_(x)Li1−_(x)V_(3−y)M_(y)O₈ electrodes of this invention.

A significant advantage of using xAgV₃O₈.(1−x)LiV₃O₈ orAg_(x)Li_(1−x)V_(3−y)M_(y)O₈ electrode is that it is possible to varythe Ag:Li ratio in the initial electrode, thus providing the opportunityto tailor and optimize the gravimetric and volumetric capacities of theelectrode and hence the gravimetric and volumetric energy densities ofthe lithium cell. For example, the theoretical gravimetric andvolumetric capacities for AgV₃O₈ are 345 mAh/g and 1518 mAh/ml,respectively, whereas for LiV₃O₈ the theoretical and volumetriccapacities are 373 mAh/g and 1350 mAh/ml, respectively (see Table 1).Furthermore, because it is believed that Ag in the crystal structure mayhinder Li⁺-ion transport in the electrode during cell operation, it isfurther believed that the power capability of the xAgV₃O₈.(1−x)LiV₃O₈ orAg_(x)Li_(1−x)V_(3−y)M_(y)O₈ electrode will be achieved by fine-tuningthe Ag:Li ratio in the initial structure.

In a third embodiment, the composite electrode consists of the AgV₃O₈,xAgV₃O₈.(1−x)LiV₃O₈ or Ag_(x)Li_(1−x)V_(3−y)M_(y)O₈ component with oneor more components selected from Ag₂V₄O₁₁, MnO₂, CF_(x), AgF and/or Ag₂Oto improve the energy density of the lithium cell. In this respect,blended (composite) electrodes comprised of Ag₂V₄O₁₁ and CF_(x) areknown in the art. Improvements in the electrochemical properties of theelectrodes and cells of the present invention can be obtained byoptionally blending the electrodes with Ag₂V₄O₁₁, MnO₂, CF_(x), AgFand/or Ag₂O.

Table 1 demonstrates from theoretical values how, in principle, theaddition of one (or more) components to a AgV₃O₈ electrode can increasethe energy density of the cell either in terms of specific energydensity (Wh/kg) and/or volumetric energy density (Wh/l). The voltage ofeach lithium cell provided in Table 1 reflects the average open circuitvoltage (OCV) of the cell during discharge, as determined from the OCVvalues that were recorded after each pulse, to an end voltage of 1.7 V.

TABLE 1 Electrochemical and physical properties of various electrodecomponents Th. Th. Li Cap. ρ Cap. Th. Energy Electrode uptake (mAh/ (g/(mAh/ Voltage Dens. Material (max) g) ml) ml) (OCV) Wh/kg Wh/l PrimaryComponent AgV₃O₈ 5 345 4.40 1518 2.65 914 4022 Secondary ComponentsLiV₃O₈ 4 373 3.62 1350 2.70 1007 3645 MnO₂ 1 308 4.83 1487 2.85 878 4241Ag₂V₄O₁₁ 7 315 4.94 1556 2.64 832 4110 CF_(x) 0.6 687 2.60 1786 ~3.02061 5359 AgF 1 211 5.85 1234 ~3.3 696 4071 Ag₂O 2 231 7.29 1683 ~3.0693 5052

In a fourth embodiment, the electrodes of this invention are mixed withAg powder which serves as an additional current collector to the carbonpowder (typically acetylene black) which is conventionally present withmetal oxide electrodes in lithium cells. Furthermore, it is believedthat the Ag powder acts as nucleating sites for the silver metal that isextruded from the AgV₃O₈, Ag₂V₄O₁₁, AgF and Ag₂O components duringdischarge, thereby enhancing the current collection at the electrode andthe power capability of the cell. Alternatively, when laminatedelectrodes are used, silver foil is used as the current collector ontowhich the electrochemically active electrode powder is cast. Thisinvention therefore extends to include silver current collectors forsilver vanadium oxide electrodes, in general, for application in lithiumelectrochemical cells and batteries.

The negative electrodes of the electrochemical cells of the presentinvention may be selected from any suitable lithium-containing compoundknown in the art, for example, metallic lithium, lithium alloys, lithiumintermetallic compounds and lithiated carbon, such as lithiated graphiteLi_(x)C₆ in which x can reach a typical value of 1. Preferably, thenegative electrode is metallic lithium.

Likewise the non-aqueous electrolyte may be selected from any suitableelectrolyte salts and solvents that are known in the art. Examples ofwell known salts are LiClO₄, LiAsF₆, LiPF₆, LiBF₄ and LiB(C₂O₄)₂, andtypical electrolyte solvents are propylene carbonate, ethylenecarbonate, diethyl carbonate, dimethyl carbonate, diethyl ether,dimethoxyethane and the like.

The principles of this invention are provided in the following examples.

Synthesis and Preparation of Electrode Materials

EXAMPLE 1

AgV₃O₈ was prepared by direct reaction of stoichiometric amounts ofNH₄VO₃ and AgNO₃ powders under oxygen at 530° C. The powder X-raydiffraction pattern of the resulting product is shown in FIG. 2.

EXAMPLE 2

LiV₃O₈ was prepared by direct reaction of stoichiometric amounts ofNH₄VO₃ and Li₂CO₃ powders in air at 550° C. The powder X-ray diffractionpattern of the resulting product is shown in FIG. 3.

EXAMPLE 3

A composite electrode powder xAgV₃O₈.(1−x)LiV₃O₈ in which x=0.5 wasprepared by milling the two separate powders of AgV₃O₈ and LiV₃O₈ underacetone (or methanol) for 3 days, followed by filtering and drying theproduct under vacuum at room temperature. The powder X-ray diffractionpattern of the resulting product is shown in FIG. 4. Although the twocomponents of this example were mixed in a 50/50 weight ratio, othervariations are specifically included in the invention.

EXAMPLE 4

Ag₂V₄O₁₁ was prepared by direct reaction of stoichiometric amounts ofNH₄VO₃ and AgNO₃ powders in air at 500° C. The powder X-ray diffractionpattern of the resulting product is shown in FIG. 5.

EXAMPLE 5

Composite electrode powders were prepared by using intimately mixedblends of the following materials:

1. AgV₃O₈:Ag₂V₄O₁₁ (95:5 ratio by weight);

2. AgV₃O₈:MnO₂ (50:50 ratio by weight);

3. AgV₃O₈/Ag₂O (97:3 ratio by weight);

4. AgV₃O₈/Ag (95:5 ratio by weight);

For these composite electrodes, the AgV₃O₈ and Ag₂V₄O₁₁ powders wereprepared as described in Examples 1 and 4, respectively. The MnO₂ wasobtained as an electrolytic manganese dioxide (EMD) from Chemetals. TheAg₂O and Ag powders were supplied by Aldrich.

Electrochemical Evaluation

In general, the lithium cells were fabricated as follows. Positiveelectrode laminates were made by the following general procedure. Theactive electrode powders were sifted to <40 μm, mixed with 8 w/o carbon(acetylene black and SFG6) and 8 w/o polyvinlyidine difluoride (PVDF)binder and cast onto an Al foil with NMP dilutant. The cast laminate wassubsequently dried at 70°, and placed into a vacuum oven overnight. Coincells of size 2032 (2.0 cm diameter, 3.2 mm high) were used for theelectrochemical evaluations. The positive electrode consisted of a 1.6cm diameter disc, punched from the laminate; a corresponding disc ofmetallic lithium, punched from lithium foil served as the negativeelectrode. Electrodes were insulated from one another by a porousCelgard separator. The electrolyte was 1 M LiAsF₆ dissolved in eitherpropylene carbonate (PC) or a 50:50 mixture of PC and dimethoxyethane(DME). The electrochemical data were collected from pulsed-currentdischarge tests (one 10-second pulse of 1 mA/cm² every fifteen minutes)of the button cells. Cells were discharged under pulse to an end voltageof at least 1.5 V. Several cells with different positive electrodematerials were constructed for which electrochemical data were collectedas defined by the following examples:

EXAMPLE 6

The 10-second pulse discharge profile of a lithium cell containing theAgV₃O₈ electrode of Example 1 is shown in FIG. 7.

EXAMPLE 7

The 10-second pulse discharge profile of a lithium cell containing theLiV₃O₈ electrode of Example 2 is shown in FIG. 8.

EXAMPLE 8

The 10-second pulse discharge profile of a lithium cell containing acomposite xAgV₃O₈.(1−x)LiV₃O₈ electrode of Example 3 is shown in FIG. 9.

EXAMPLE 9

The 10-second pulse discharge profiles of lithium cells containing thecomposite electrodes AgV₃O₈/MnO₂; AgV₃O₈/Ag₂O; and AgV₃O₈/Ag of Example5 are shown in FIGS. 10, 11 and 12, respectively.

The total capacities of each of the electrodes in Examples 6-9,delivered to an end voltage of 1.7 V and the corresponding energydensities of the lithium cells, are summarized in Tables 2 and 3, whichdemonstrates the utility of the electrode materials of this invention.

EXAMPLE 10

Ten-second pulse discharge profiles of lithium button cells containingAgV₃O₈ and Ag₂V₄O₁₁ electrodes with Al and Ag foil current collectorswere collected in the same manner as described in the foregoingexamples. The results of these experiments are summarized in Table 3;the data show how the specific capacity of both types of silver vanadiumoxide electrode, i.e., not only AgV₃O₈but also Ag₂V₄O₁₁, can besignificantly improved by changing the current collector at the positiveelectrode from aluminum foil to silver foil, which also results in asignificant improvement in the energy density of the lithium cell.

TABLE 2 Performance data of various electrodes Specific Capacity EnergyDensity Electrode Material (mAh/g) (mWh/cm³) AgV₃O₈ 284 3049 LiV₃O₈ 2792325 xAgV₃O₈.(1 − x)LiV₃O₈ 218 2032 AgV₃O₈/MnO₂ 241 2822 AgV₃O₈/Ag₂O 2442681 AgV₃O₈/Ag 265 3097

TABLE 3 Performance data of AgV₃O₈ and Ag₂V₄O₁₁ electrodes with Ag andAl foil current collectors Current Specific Capacity Energy DensityElectrode Material Collector (mAh/g) (mWh/cm³) AgV₃O₈ Al 248 2666 AgV₃O₈Ag 348 3799 Ag₂V₄O₁₁ Al 286 3474 Ag₂V₄O₁₁ Ag 306 3652

This invention, therefore, relates to positive electrodes and currentcollectors for a non-aqueous electrochemical lithium cell, as shownschematically in FIG. 13, the cell represented by the numeral 10 havinga negative electrode 12 separated from a positive electrode 16 by anelectrolyte 14, all contained in an insulating housing 18 with suitableterminals (not shown) being provided in electronic contact with thenegative electrode 12 and the positive electrode 16. Negative electrode12 may be LiV₃O₈, Ag₂V₄O₁₁, MnO₂, CF_(x), AgF or Ag₂O with metalliclithium preferred. Binders and other materials normally associated withboth the electrolyte and the negative and positive electrodes are wellknown in the art and are not described herein, but are included as isunderstood by those of ordinary skill in this art. FIG. 14 shows aschematic illustration of one example of a battery in which two stringsof electrochemical lithium cells, described above, are arranged inparallel, each string comprising three cells arranged in series.

While particular embodiments of the present invention have been shownand described, it will be appreciated by those skilled in the art thatchanges, modifications and improvements may be made without departingfrom the true spirit and scope of the invention.

1. A positive electrode for a non-aqueous lithium cell havingelectroactive material consisting of a composite metal oxide containingAgV₃O₈ as one component, and one or more additional components selectedfrom the group consisting of LiV₃O₈, Ag₂V₄O₁₁, MnO₂, CF_(x), AgF orAg₂O.
 2. The positive electrode of claim 1, wherein the additionalcomponents are selected from LiV₃O₈ and Ag₂V₄O₁₁.
 3. The positiveelectrode of claim 2, wherein the composite metal oxide is a solidsolution of xAgV₃O₈.(1−x)LiV₃O₈ or Ag_(x)Li_(1−x)V₃O₈.
 4. The positiveelectrode of claim 3, wherein the composite metal oxide isAg_(x)Li_(1−x)V_(3−y)M_(y)O₈, in which 0<x<1 and 0<y<1.5, and in which Mis one or more monovalent or multivalent transition metals.
 5. Thepositive electrode of claim 4, wherein the M ions are selected from oneor more of Ti, Y, Zr, Nb and Mo ions.
 6. The positive electrode of claim4 in which the electrode contains a current collector of silver powderor silver foil or both.
 7. The positive electrode of claim 1 in whichthe electrode contains a silver powder or silver foil current collector.8. A non-aqueous lithium electrochemical cell comprising a negativeelectrode, an electrolyte and a positive electrode, the positiveelectrode having electroactive material consisting of a composite metaloxide containing AgV₃O₈ as one component, and one or more additionalcomponents selected from the group consisting of LiV₃O₈, Ag₂V₄O₁₁, MnO₂,CF_(x), AgF or Ag₂O.
 9. The non-aqueous lithium electrochemical cell ofclaim 8 in which the positive electrode contains a silver powder orsilver foil current collector.
 10. The non-aqueous lithiumelectrochemical cell of claim 8 in which the negative electrode isselected from metallic lithium, lithium alloys, lithium intermetalliccompounds and lithiated carbon.
 11. The non-aqueous lithiumelectrochemical cell of claim 8 in which the negative electrode ismetallic lithium.
 12. The non-aqueous lithium electrochemical cell ofclaim 8, wherein the cathode is selected from LiV₃O₈ and Ag₂V₄O₁₁. 13.The non-aqueous lithium electrochemical cell of claim 8, wherein thecomposite metal oxide in a solid solution xAgV₃O₈.(1−x)LiV₃O₈ orAg_(x)Li_(1−x)V₃O₈.
 14. The non-aqueous lithium electrochemical cell ofclaim 8, wherein the composite metal oxide isAg_(x)Li_(1−x)V_(3−y)M_(y)O₈, in which 0<x<1 and 0<y<1.5, and in which Mis one or more monovalent or multivalent transition metals.
 15. Thenon-aqueous lithium electrochemical cell of claim 14 in which theelectrode contains a silver powder or silver foil current collector. 16.The positive electrode of claim 15 in which the electrode contains acurrent collector of silver powder or silver foil or both.
 17. Thenon-aqueous lithium electrochemical cell of claim 8, wherein the M ionsare selected from one or more of Ti, Y, Zr, Nb and Mo ions.
 18. Anon-aqueous lithium battery comprising a plurality of electrochemicalcells, electrically connected, each cell comprising a negativeelectrode, an electrolyte and a positive electrode, the positiveelectrode having electroactive material consisting of a composite metaloxide containing AgV₃O₈ as one component, and one or more additionalcomponents selected from the group consisting of LiV₃O₈, Ag₂V₄O₁₁, MnO₂,CF_(x), AgF or Ag₂O.
 19. A non-aqueous lithium battery of claim 18, inwhich the positive electrode of each electrochemical cell contains asilver powder or silver foil current collector.
 20. A non-aqueouslithium battery of claim 18, in which the negative electrode of eachelectrochemical cell is selected from metallic lithium, lithium alloys,lithium intermetallic compounds and lithiated carbon.
 21. A non-aqueouslithium battery of claim 18, in which the negative electrode of eachelectrochemical cell is metallic lithium.
 22. The non-aqueous lithiumelectrochemical battery of claim 18, wherein the cathode is selectedfrom LiV₃O₈ and Ag₂V₄O₁₁.
 23. The non-aqueous lithium electrochemicalbattery of claim 18, wherein the composite metal oxide in a solidsolution of xAgV₃O₈.(1−x)LiV₃O₈ or Ag_(x)Li_(1−x)V₃O₈.
 24. Thenon-aqueous lithium electrochemical battery of claim 18, wherein thecomposite metal oxide is Ag_(x)Li_(1−x)V_(3−y)M_(y)O₈, in which 0<x<1and 0<y<1.5, and in which M is one more monovalent or multivalenttransition metals.
 25. The non-aqueous lithium electrochemical batteryof claim 24 in which the electrode contains a silver powder or silverfoil current collector.
 26. The non-aqueous lithium electrochemicalbattery of claim 18, wherein the M ions are selected from one or more ofTi, Y, Zr, Nb and Mo ions.
 27. A non-aqueous lithium electrochemicalcell having electroactive material consisting of a negative electrode,an electrolyte and a positive electrode, the positive electrodecomprising AgV₃O₈ as one component, and one or more additionalcomponents selected from the group consisting of LiV₃O₈, Ag₂V₄O₁₁, MnO₂,CF_(x), AgF or Ag₂O.
 28. The non-aqueous lithium electrochemical cell ofclaim 27, wherein the current collector is powder or foil.
 29. Anon-aqueous lithium battery comprising a plurality of electrochemicalcells electrically connected, each cell comprising a negative electrode,an electrolyte and a positive electrode, the electroactive materialconsisting of a composite metal oxide containing AgV₃O₈ as onecomponent, and one or more additional components selected from the groupconsisting of LiV₃O₈, Ag₂V₄O₁₁, MnO₂, CF_(x), AgF or Ag₂O.
 30. Thenon-aqueous lithium electrochemical cell of claim 29, wherein thecurrent collector is powder or foil.